Oxidation and coagulation/adsorption dual effects of ferrate (VI) pretreatment on organics removal and membrane fouling alleviation in UF process during secondary effluent treatment

An Ding; Zixiao Ren; Lei Hu; Rourou Zhang; Huu Hao Ngo; Dongwei Lv; Jun Nan; Guibai Li; Jun Ma

doi:10.1016/j.scitotenv.2022.157986

Oxidation and coagulation/adsorption dual effects of ferrate (VI) pretreatment on organics removal and membrane fouling alleviation in UF process during secondary effluent treatment

Sci Total Environ. 2022 Dec 1:850:157986. doi: 10.1016/j.scitotenv.2022.157986. Epub 2022 Aug 10.

Authors

An Ding¹, Zixiao Ren², Lei Hu², Rourou Zhang², Huu Hao Ngo³, Dongwei Lv², Jun Nan², Guibai Li², Jun Ma²

Affiliations

¹ State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, PR China. Electronic address: dinganhit@163.com.
² State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, PR China.
³ Faculty of Engineering, University of Technology Sydney, P.O. Box 123, Broadway, Sydney, NSW 2007, Australia.

PMID: 35963402
DOI: 10.1016/j.scitotenv.2022.157986

Abstract

Ultrafiltration (UF) has been widely used in water and advanced sewage treatment. Unfortunately, membrane fouling is still the main obstacle to further improvement in the system. Fe (III) salt, a type of traditional coagulant, is often applied to mitigate UF membrane fouling. However, low molecule organic weight cannot be effectively removed, thus the water quality after single coagulation treatment does not effectively meet the standard of subsequent water reuse during secondary effluent treatment. Recently, it has been found that potassium ferrate (Fe (VI)) has multiple functions of oxidation, sterilization and coagulation, with other studies proving its good performance in organics removal and membrane fouling mitigation. However, the respective contributions of oxidation and coagulation/adsorption have not yet been fully understood. The oxidation and coagulation/adsorption effects of Fe (VI) during membrane fouling mitigation were investigated here. The oxidation effect of Fe (VI) was the main reason for organics with the MW of 8-20 kDa removal, and its coagulation/adsorption mainly accounted for the smaller amounts of molecular organics removed. The oxidation of Fe (VI) was the main method for overcoming membrane fouling in the initial filtration; it largely alleviated the standard blockage. The formation of a cake layer transformed the main membrane fouling alleviation mechanism from oxidation to coagulation/adsorption and further removed smaller amounts of molecule organics with the increase of filtration cycles and Fe (VI) dosages. The main fouling mechanism altered from standard blocking and cake filtration to only cake filtration after Fe (VI) treatment. Overall, the mechanism of the oxidation and coagulation/adsorption of Fe (VI) were differentiated, and would provide a reference for future Fe (VI) pretreatment in UF membrane fouling control during water and wastewater treatments.

Keywords: Membrane fouling mechanism; Oxidation/coagulation; Potassium ferrate; Ultrafiltration; Wastewater reuse.

MeSH terms

Adsorption
Iron
Membranes, Artificial
Sewage
Ultrafiltration* / methods
Wastewater
Water Purification* / methods

Substances

Membranes, Artificial
Sewage
Waste Water
ferrate ion
Iron